 (defn- deps-from-ns-form [form]
   (when (and (list? form)
 	     (contains? #{:use :require} (first form)))
-    (apply union (map #(deps-from-libspec nil %) (rest form)))))
+    (apply set/union (map #(deps-from-libspec nil %) (rest form)))))
 
 (defn deps-from-ns-decl
   "Given a (quoted) ns declaration, returns a set of symbols naming
   the dependencies of that namespace.  Handles :use and :require
   clauses but not :load."
   [decl]
-  (apply union (map deps-from-ns-form decl)))
+  (apply set/union (map deps-from-ns-form decl)))

  ^{:author "Stuart Sierra",
     :doc "Search for ns declarations in dirs, JARs, or CLASSPATH"} 
  clojure.tools.namespace
  (:require [clojure.java.classpath :as classpath])
  (import (java.io File FileReader BufferedReader PushbackReader
                   InputStreamReader)
          (java.util.jar JarFile)))

;;; Parsing dependencies

(defn- deps-from-libspec [prefix form]
  (cond (list? form) (apply set/union (map (fn [f] (deps-from-libspec
						(symbol (str (when prefix (str prefix "."))
							     (first form)))
						f))
